Ochratoxin A and Aflatoxins: Fine-Tuning to the ELISA Test on Table Olives

Abstract

This study is aimed to point out the possible application of the Enzyme-Linked ImmunoSorbent Assay (ELISA) test on table olives. Because olives, like many other foods, are not free from mycotoxin contamination, the main focus of this work was assessing the presence or absence of aflatoxins and ochratoxin A. The work was carried out in two phases. In the first phase, tests were carried out on commercial olives to assess the efficacy of the method and the kit (Veratox® 'Neogen' and AgraQuant® 'Romer Labs') by comparing them with the Liquid Chromatography coupled to a mass-mass spectrometer (LC-MS/MS); in order to understand if there were any interferences in antigen-antibody recognition; subsequently, mycotoxins were inoculated on the same samples with a known quantity, in order to assess the concentrations obtained and compare them to the expected ones. The second step involved modifying the method, so to improve the recovery of inoculated mycotoxins in the samples under study. Afterwards we evaluated the presence of mycotoxins in table olives supplied in the project. The results showed the effectiveness of the ELISA test, especially in the mycotoxin recovery phase. Indeed, after the modification of the mycotoxin extraction method, recoveries increased from 55% to over 70% for aflatoxins, and from 40% to over 55% for ochratoxin A. When analysing the samples provided by the above-mentioned company, the results showed some false positives, in particular in relation to ochratoxin A ’s analysis, mainly related to the first sample submission. Taking this into account, the ELISA test can be considered as an initial screening method applicable as a control programme for the evaluation of mycotoxins in olives which helps by saving time and costs. It should always be kept in mind that, if positive values should emerge, the LC-MS/MS analysis should be carried out.